@Blackdog this is what I'm getting at. Replacing the rubber "pip" is an excellent idea at first glance, though maybe not so much in practice. Yeah, the links are fine, I guess, if a little confusing to ping-pong around. What PSI specification were the caps designed to release?
I think that @exeter_yak , @kerophile and BernieDawg posted that information, many years ago. I'll see if I can locate it, and post it here. - Doc PS - Check out this thread, for some good, and hopefully, interesting related information: SRV Cap Tester/Setter
I can quote 2 examples of this type of stove going astray but only one was an explosion. First a stove I now own opened its safety while simmering. It was described as a small flame coming out which slowly got bigger till it was about a meter long. Owner took pot off and turned to full and the flame shrunk and went out. Stove was a Optimus 42. Second which was more exciting was a Primus 70 or similar. I was at school still with no understanding of stoves. A hunter in a hut we were also staying in owned the stove. It started to flare around the base of the burner. He grabbed it by the lid at arms length and headed for the door. He just got to the door and there was a very loud bang and he was left holding a case and font. The burner was never found despite looking for it. The explosion went out the door so no damage or injuries luckily
Sounds very much like the burner threads had been damaged by overtightening in the past, to the point where they were stripped by the pressure.
This stove tinkering is addictive, against all logic I have ordered another tank from fogas. Will not be using stand or windshield in the future and will be winding the SRV penta screw out a few turns. Will then check for the candle flame and adjust as required. Thanks for your help and I am glad I didn't keep it a secret.
No ideal of pressure, this happened while out using the stove in the field. Another thought I have is the burner was over fired and the wicks quite loose in the riser. I am going to replace the wick with fibreglass and make it tighter fitting, I rebuilding the stove with a new tank. I am of course comparing the flame with my 8r stove that I have used extensively
I thought it would be most helpful for the information to be included here in this thread, instead of a link-o-rama, was my point.
Ok, I see your point, however when dealing with a subject as safety critical as setting safety valves of self-pressurising tanks full of highly volatile fuel, I think it is better to read fully around the subject before making decisions, including understanding figures in the context they are given. Especially as in one of the threads I linked to, the 'official Optimus' settings are quoted as 'somebody says this is what the official catalogue/instruction book says', as opposed to a scan of said literature. With a subject like this, I'm particularly wary of stating things simply, as fact, because that's what they become in time, correctly or otherwise.
The term Swedish Handgrenade is an overblown term. Even the title term disaster implies there is more disaster to this than there was. No photos, and all these second hand stories inflate the already overblown misconception that the stove is a disaster waiting to happen. That is not the case. It is a safety feature built in. Idiot-proof even.
While I do wish I had photos, I don't. It takes only a little imagination to visualise a concave base. Yes, it failed safe and it would have to been left far longer for it to have become dangerous. The SRV would have worked eventually, although a little late. I have been using the old faithful this weekend, 8r without problems. The flame is blue and a lot more stable, easily controlled.
On balance I’ve heard of the SRV letting go on the 8R far more frequently than the 123, this is usually attributed to larger frying pans or pots, reflecting excessive heat on the fuel tank.
Even after warming up, and new nozzle the flame had yellow tips. This was Even at low fire or simmer, the flame only blueish at high fire. Still should be able to have another go when replacement tank arrives. As mentioned earlier, might replace the wick with a tighter fitting one. To possibly reduce the fuel flow, to act like a restriction orifice.
Interesting, so something was wrong with the air/fuel ratio, but I can't see how that could result in the overpressuring. Rather than trying to restrict the fuel flow, it would be better to solve the problem of why it is not burning pure blue at all regulator settings, there are hundreds of thousands of these stoves, if not milions, which work reliably. We like a challenge, this has the feeling of turning into an interesting saga!
